What has journaling done for you, that couldn't be done with honest, and regular self-reflection?
An outlet for the unfiltered stream of consciousness is important. You just write whatever comes up. No-one else is to read it. That's equally important.
As a result, I'm happier and more creative. But if you want to start, I wouldn't advise focussing on the benefits too much. In all likelihood, you'll start because you need to, or because the time is right. Hope that helps!
I try to journal every day and have been since around 2014. The main "benefit" is the ability to look at a random date (say, Jan 19th 2015) and know what I was up to that day/period.
I started journaling hoping it would help clarify my thoughts/reveal something dormant in my mind. It did neither.
One odd quirk: If I'm really deep in a depressive hole, I can identify that by writing a journal entry. If I start freewriting and the content is getting progressively worse (usually devolving into sentence after sentence telling myself to grow up and kill myself), I can sometimes "trick" my brain into realizing I'm in a depressive hole and the world isn't actually an awful place.
It's hard to explain, but the ability to "see" my brain thinking in a downward loop sometimes helps to trigger my rational brain.
On the flip side, in some rare instances if I journal while depressed, it dramatically increases my misery. Instead of just thinking I'm hopeless, it can work as a mental reinforcement that everything I'm writing is true. Journling while depressed is like playing Russian roulette.
Overall, I don't find journaling that beneficial.
There is medical evidence that it helps in depression. It might not elevate your mood the same time but you can see the pattern and how stupid your thoughts are some time.
/badjoke
This summer I’ve been kind of depressed being unemployed and haven’t done it but it probably would have helped.